function [] = func4()
    x=linspace(-8*pi,8*pi,400);
    y1 = sin(2*x);
    y2 = cos(2*x);
    figure(1)
    plot(x,y1,'r-',x,y2,'g--');
    title('y1&y2');
    figure(2)
    subplot(2,1,1);
    plot(x,y1,'r-');
    title('y1');
    subplot(2,1,2);
    plot(x,y2,'g--');
    title('y2');
end